As a widely-used processing apparatus, a magnetron sputtering apparatus is mainly used in deposition process of a work piece such as a substrate. The basic principle of the magnetron sputtering is as follows: a reaction gas is excited to form plasma, which is used for bombarding a target material disposed in a reaction chamber, such that particles escape from a surface of the target material and then are deposited on a work piece. In fabrication of semiconductor devices of very large-scale integration, a metal layer is generally required to be deposited in a channel, trench or via having a large depth-to-width ratio on a surface of a work piece, and thus concentration of the plasma is required to be increased in the reaction chamber.
Referring to FIGS. 1 and 2A, an existing reaction chamber is illustrated. The reaction chamber 10 is provided with an induction coil 11 surrounding outer sides of side walls thereof, which is electrically connected with a radio frequency (RF) power supply 12 via a matcher 13 and configured to generate an alternating magnetic field in the reaction chamber 10, such that a processing gas in the reaction chamber 10 is excited by energy of the alternating magnetic field to form plasma. In practical processes, a metal film may be deposited on the inner side walls of the reaction chamber 10 while depositing a metal film on a work piece S, that is, a closed metal ring is nested on the inner side walls, which will lead to an induced current generated in the metal ring by the alternating magnetic field generated from the induction coil 11, so that the alternating magnetic field generated from the induction coil 11 is shielded. For this reason, the reaction chamber 10 is generally provided with a Faraday shielding ring 14 having a cylindrical structure, which surrounds the inner side walls of the reaction chamber 10. The Faraday shielding ring 14 is made of a magnetic insulation material and provided with a slot (not shown in the figures) thereon at the ring surface thereof, which passes through the ring surface thereof in an axial direction, so that the Faraday shielding ring 14 is unclosed in its circumferential direction.
Referring to FIG. 2B, a plan view of a conventional Faraday shielding ring is illustrated. The Faraday shielding ring 14 is of a cylindrical structure and unclosed in its circumferential direction. Specifically, a slot is provided at the ring surface of the Faraday shielding ring 14, which passes through the Faraday shielding ring 14 along an axial direction of the Faraday shielding ring 14. The slot is provided as a teeth-shaped slot 141. The so-called teeth-shaped slot 141 refers to that a projection of the slot 141 on a plane perpendicular to the axial direction of the Faraday shielding ring 14 appears as a shape similar to the character “Z”. That is, a portion of the projection of the slot 141 facing the inner side of the reaction chamber 10 and a portion of the projection of the slot 141 distal to the inner side of the reaction chamber 10 are similar to a pair of teeth-shaped protrusions. The Faraday shielding ring 14 having the “Z” type teeth-shaped slot 141 is also referred to as a “Labyrinth Slot Faraday Shielding Ring”. By employing such an unclosed Faraday shielding ring 14, a metal film can be prevented from being deposited and formed on the inner side walls of the reaction chamber 10, and a conductive path can be prevented from being formed in the Faraday shielding ring 14, so that energy of the alternating magnetic field generated from the induction coil 11 can be coupled into the reaction chamber 10.
In addition, at the bottom area of the reaction chamber 10, a lining member 16, which is generally made of a metal material and grounded, is provided surrounding the inner side walls of the reaction chamber 10. The lining member 16 is of a stepped shape, in which an upper step surface of the lining member 16 is a plane, and a lower step surface thereof is a bottom 161 of a recess of the lining member. An insulating ring 17, made of an insulating material such as quartz or ceramic, is stacked on the upper surface of the lining member 16, and a lower surface of the Faraday shielding ring 14 is stacked on an upper surface of the insulating ring 17. In order to prevent the Faraday shielding ring 14 from being closed at the slotted position of its lower surface when depositing metal particles on the upper surface of the insulating ring 17 in a process, a lower end of the Faraday shielding ring 14 is set to have a stepped shape, that is, an inner area of the lower surface of the Faraday shielding ring 14, which is adjacent to the center of the reaction chamber 10, is formed as a recess 15 that is recessed towards the upper surface of the Faraday shielding ring 14. Moreover, in order to prevent the slot of the Faraday shielding ring 14 from being closed, it is required that the dimension of the recess 15 in a horizontal direction is relatively large, that is, it is required that a thickness of the Faraday shielding ring 14 is relatively large in its radial direction.
In practical applications, the reaction chamber 10 as described above inevitably experiences the following problems. In a case where an up-to-down exhausting manner is employed in the reaction chamber 10, a majority of metal particles move downwards in a vertical direction. In this case, as the insulating ring 17 is stacked between the Faraday shielding ring 14 and the lining member 16, and an inner circumferential surface, a portion of the upper surface and a portion of the lower surface of the insulating ring 17 are exposed to the interior of the reaction chamber 10, metal particles are easily deposited on the upper surface of the insulating ring 17 when the process proceeds, causing that the Faraday shielding ring 14 becomes closed at the slotted position of its lower surface, and thus a spark phenomenon occurs at the slotted position and the process is affected. Further, as the inner circumferential surface, the portion of the upper surface and the portion of the lower surface of the insulating ring 17 are exposed to the interior of the reaction chamber 10, when metal particles deposited thereon flake off, the reaction chamber 10 is easily polluted by the particles, which may damage the work piece S severely.